1. Technical Field
The present invention relates to a method of manufacturing an electrophoretic particle, an electrophoretic particle, an electrophoretic dispersion, an electrophoretic sheet, an electrophoretic device, and an electronic apparatus.
2. Related Art
Generally, it is known that, when an electric field is applied to a dispersion system in which particles are dispersed in a liquid, particles are moved (migrated) in a liquid by the Coulomb force. This phenomenon is referred to as electrophoresis. Recently, an electrophoretic display device displaying desired information (image) using this electrophoresis has attracted attention as a new display device.
This electrophoretic display device is characterized in that it has display memory properties and wide viewing angle properties in a state in which the application of a voltage is stopped, and in that high-contrast display is possible with low power consumption.
Further, the electrophoretic display device is also characterized in that it is easy on the eyes compared to a light-emitting display device such as Braun tube because it is a non-emitting display device.
It is known that such an electrophoretic display device has an electrophoretic dispersion, in which electrophoretic particles are dispersed in a solvent, between a pair of substrates having electrodes.
In the electrophoretic dispersion having such a configuration, electrophoretic particles including positively-charged particles and negatively-charged particles are used. Thus, when a voltage is applied between a pair of substrates (electrodes), it is possible to display desired information (image).
Referring to FIG. 10, generally, an electrophoretic particle 501 including a base particle 502 and a coating layer 503 consisting of polymers 533 bonded to the base particle 502 is used. As such, since the electrophoretic particle 501 is configured to have such a coating layer 503 (polymers 533), it is possible to disperse and charge the electrophoretic particles 501 in an electrophoretic dispersion.
Meanwhile, the electrophoretic particle having such a configuration, for example, is manufactured using atom transfer radical polymerization (ATRP) as follows.
That is, a base particle 502 is prepared, silane coupling agents 531 each having a polymerization initiation group are bonded to the surface of the base particle 502, and then monomers are polymerized by living radical polymerization based on this polymerization initiation group as a starting point, so as to form polymerized units 532. Then, these polymerized units 532 are grown to provide polymers 533. Through these procedures, properties such as chargeability and dispersibility are imparted, thereby manufacturing the electrophoretic particle 501 (for example, referring to JP-A-2013-156381).
In the electrophoretic particle 501 manufactured using such ATRP, the polymer 533 is produced by polymerizing monomers based on this polymerization initiation group (as a starting point) included in the silane coupling agent bonded to the surface of the base particle 502 to form the polymerized unit 532. In this case, according to the density of the silane coupling agent bonded to the base particle 502 and the kind of monomer, in the molecular weight of the polymerized unit 532 in the produced polymer 533, that is, in the polymerization degree of monomer, there are variations between the adjacent polymerized units 532.
Therefore, there is a problem in that uniform dispersibility cannot be obtained between a plurality of electrophoretic particles contained in an electrophoretic dispersion.